The neural correlates of orienting to walking direction in 6‐month‐old infants: An ERP study

The ability to detect social signals represents a first step to enter our social world. Behavioral evidence has demonstrated that 6‐month‐old infants are able to orient their attention toward the position indicated by walking direction, showing faster orienting responses toward stimuli cued by the direction of motion than toward uncued stimuli. The present study investigated the neural mechanisms underpinning this attentional priming effect by using a spatial cueing paradigm and recording EEG (Geodesic System 128 channels) from 6‐month‐old infants. Infants were presented with a central point‐light walker followed by a single peripheral target. The target appeared randomly at a position either congruent or incongruent with the walking direction of the cue. We examined infants' target‐locked event‐related potential (ERP) responses and we used cortical source analysis to explore which brain regions gave rise to the ERP responses. The P1 component and saccade latencies toward the peripheral target were modulated by the congruency between the walking direction of the cue and the position of the target. Infants' saccade latencies were faster in response to targets appearing at congruent spatial locations. The P1 component was larger in response to congruent than to incongruent targets and a similar congruency effect was found with cortical source analysis in the parahippocampal gyrus and the anterior fusiform gyrus. Overall, these findings suggest that a type of biological motion like the one of a vertebrate walking on the legs can trigger covert orienting of attention in 6‐month‐old infants, enabling enhancement of neural activity related to visual processing of potentially relevant information as well as a facilitation of oculomotor responses to stimuli appearing at the attended location.     

基于自发脑电的脑机接口研究进展

脑机接口是一种不依赖于外周神经和肌肉等常规输出通道的信息交流系统,近年来发展非常迅速。它可为神经肌肉障碍患者提供一条与外界沟通的途径,并在虚拟现实、游戏娱乐和航空等领域具有潜在价值。目前,脑机接口中常用的脑电输入信号包括P300、稳态视觉诱发电位（SS—VEP）、皮层慢电位（SCP）以及μ或β节律等。其中,SCP、μ或β节律等自发脑电不依赖于额外刺激的输入,不会产生视觉疲劳,没有适应性的问题,且其神经生理学基础已获得比较深入的研究,因而在脑机接口中得到了较多的应用。但是,基于自发脑电的脑机接口也存在明显的缺陷,如并非所有个体都适用基于汕节律的脑机接口,基于SCP的脑机接口要经过长时间的训练才能实现等。     

Trial-to-trial dynamics of selective long-term-memory retrieval with continuously changing retrieval targets

How do we control the successive retrieval of behaviorally relevant information from long-term memory (LTM) without being distracted by other potential retrieval targets associated to the same retrieval cues? Here, we approach this question by investigating the nature of trial-by-trial dynamics of selective LTM retrieval, i.e., in how far retrieval in one trial has detrimental or facilitatory effects on selective retrieval in the following trial. Participants first learned associations between retrieval cues and targets, with one cue always being linked to three targets, forming small associative networks. In successive trials, participants had to access either the same or a different target belonging to either the same or a different cue. We found that retrieval times were faster for targets that had already been relevant in the previous trial, with this facilitatory effect being substantially weaker when the associative network changed in which the targets were embedded. Moreover, staying within the same network still had a facilitatory effect even if the target changed, which became evident in a relatively higher memory performance in comparison to a network change. Furthermore, event-related brain potentials (ERPs) showed topographically and temporally dissociable correlates of these effects, suggesting that they result from combined influences of distinct processes that aid memory retrieval when relevant and irrelevant targets change their status from trial to trial. Taken together, the present study provides insight into the different processing stages of memory retrieval when fast switches between retrieval targets are required.     

Perceptual Learning

The extent of adult improvement in not only complex but also simple perceptual tasks is remarkable. Although this phenomenon has been noted and studied since the middle of the 19th century, recent advances in the study of brain physiology and anatomy afford new insights. Improvement specificity suggests that changes involve early sensory cortical areas, previously thought to lose their plasticity following the first years. The critical role of selective attention, even in learning the simplest tasks, as well as the precedence of learning easy cases, suggests the involvement of high-level cortical areas. Learning easy cases is more general than learning difficult cases. This pattern suggests the involvement of both high- and low-level areas in an orderly manner, with easy learning beginning at high-level areas and harder cases being resolved by access to low-level areas. The mapping of behavioral findings to underlying brain sites provides a unified framework for this interdisciplinary field.     

Precis of <Emphasis Type="Italic">Philosophy and Neuroscience</Emphasis>: <Emphasis Type="Italic">A Ruthlessly Reductive Account</Emphasis>

This book precis describes the motives behind my recent attempt to bring to bear “ruthlessly reductive” results from cellular and molecular neuroscience onto issues in the philosophy of mind. Since readers of this journal will probably be most interested in results addressing features of conscious experience, I highlight these most prominently. My main challenge is that philosophers (even scientifically-inspired ones) are missing the nature and scope of reductionism in contemporary neuroscience by focusing exclusively on higher-level cognitive neuroscience, and ignoring the discipline's cell-physiological and molecular-biological core.     

睡眠研究若干现代理论问题

最近十年间睡眠研究日益引起全世界的重视,除我国等纷纷建立“睡眠研究会”外,并新 建“亚洲睡眠研究会”和“世界睡眠研究联合会”。本文探讨睡眠研究的若干现代理论问题,其 中包括睡眠的核心是深度慢波睡眠问题,睡眠如何受制于“２４－ｈ昼夜节律”,异相睡眠和觉醒 的比较分析,世界范围内重新评价午睡的重要性,临床睡眠疾患及其对策和介诏内源性促眠物质等。     

Danger and usefulness are detected early in auditory lexical processing: evidence from electroencephalography

Visual emotionally charged stimuli have been shown to elicit early electrophysiological responses (e.g., [Ihssen et al., 2007], [Schupp et al., 2003] and [Stolarova et al., 2006]). We presented isolated words to listeners, and observed, using generalized additive modeling, oscillations in the upper part of the delta range, the theta range (Bastiaansen & Hagoort, 2003), and the lower part of the alpha range related to degree of (rated) danger and usefulness (Wurm, 2007) starting around 150 ms and continuing to 350 ms post stimulus onset. A negative deflection in the oscillations tied to danger around 250-300 ms fits well with a similar negativity observed in the same time interval for visual emotion processing. Frequency and competitor effects emerged or reached maximal amplitude later, around or following the uniqueness point. The early effect of danger, long before the words’ uniqueness points, is interpreted as evidence for the dual pathway theory of LeDoux (1996).